C++ :: How To Delete A Memory Leak

is there a way to delete a memory leak ? like when the pointer is no longer pointing to that memory address, and that allocated memory is not accessible, how can i delete that ?

sample:

int *p = new int;
*p = 5;
//if i dont't delete p here, is that a way to deallocate the dynamically allocated variable above ?
p = new int; //since p is no longer pointing to 5, and there's no way of accessing it
*p = 10
delete p; //i know this only deallocates the memory address which holds 10, not the one before